I just picked up my 1LE yesterday from a dealer 150 miles from home. The car had 117 miles on the clock at pickup, no idea how it was driven as these were probably test drives. The 150 was a combination of highway at 65 and short 25 - 35 mph stints through small towns. Also some mountain pass driving at speed. If I drain the oil and replace with non-synthetic should I just work it hard for the rest of the 500 miles, or do a complete 500 before switching back to synthetic?